The number and types of animals grazing an area should be carefully considered based on the  resources  available in the region.   After the  animals  are  introduced  to the  area, grazing must be controlled so that the animals range uniformly over a large area and do not destroy one section. If animals are allowed to graze one area continuously,  they will overgraze it.   Strategic positioning  of salt blocks  can be used to induce  animals to go through areas that they do not normally graze in order to reach a water source (Owen et al. 330).

Overgrazing also  causes problems for our livestock.   The most nutritious  plants will be eaten first,  leaving only those with little nutritional value for the herd.   To avoid this, pastures can be fenced off,  leaving only specific  areas open for grazing at any one time.  One example of this is to use an area one year, then bar access to this area the next year.  By rotating stock to different pastures all of the pastures will have time to recover from the  pressures of grazing.   This type of planning  will  benefit both  the grasses  and the underlying soil.
 
 

For hundreds of years man has farmed on the earth.  During this time the world’s popu- lation has grown enormously.   Because of this, it is necessary for us to farm larger and larger areas of  land to keep everyone fed.   This pressure to provide for our species has caused us to  overuse the land which we  have to the extent that the soil is very poor in nutrients.  In addition, in many areas of the world it is very thin.  It is now believed that soil depletion is one of the main reasons that many important societies in the past have failed.

As in the case of livestock management,  it is important that we manage our land when farming also.   If we rotate the fields which we use for cultivation, the fields will have a chance to recover between uses.  Another alternative is to plant different types of crops on the fields.  Different species utilize different nutrients from the soil.  Because of this, important nutrients are not all devoured by one plant species.

Erosion has also become a major problem on our farms.  Because our fields are never given a chance to  recover  between  growing seasons,  much of our  soil is  simply  eroded away.  This erosion often causes problems far away from the source.  Many water sources become filled   with  sediments to  the  extent  that  they  become  unfit as  habitats  for  aquatic species.  In addition, too much sediment in the water causes us problems when we have to treat the water further before it can be used for human consumption.

Another problem with our farming practices is the use of pesticides and fertilizers to ensure more  productivity of our crops.   The costs of  farming are quite high,  and it is natural  or farmers to  want to obtain the  largest harvest they can to  offset their oper-
ating expenses.  However, the pesticides which we use on our crops harm more than just the intended pest species we hope to kill.   They are washed away  in the rain into our groundwater sources and eventually into our rivers and oceans.  These toxins are deadly to many species of animals and fish.  We have alternatives to these large portions of pesticides.  These are explained in some detail in the page on Integrated Pest Management.
 
 

FOREST RESOURCES The United States Forest Service tries to make our forest resources available to the greatest number of Americans possible.  This requires a delicate balancing act that calls for complex decisions and considerations.  The needs of the people in the area must be weighed when deciding how to manage the resources.

One major  use of forests  is as source of lumber.   In this capacity  they provide needed materials for housing and development, and as a side benefit they provide numerous
jobs for locals.  Yet, we have to be careful not to overharvest our forests to the extent that they are unable to recover.  Sustainable harvesting of lumber must be practiced if
we intend to have these resources in the future.

Currently in many areas the amount of timber cut is greater than the growth of the forest (Owen et al. 343).  For the forest to be maintained, the amount harvested annually must be equal to or less than the amount produced.  One method which can be used to achieve this is to only cut trees of a certain age and leave younger ones standing.  These younger trees can then develop into mature trees in a few years.  Another alternative is to harvest only a certain percentage of trees in a given area.  In this way there is always a reserve of wood left in the forest.  There are many other ways in which harvesting can be done sus-
tainably, and it is our responsibility to evaluate these before we begin clearing forests.

Forests are also vitally important in flood and erosion control.  The loss of vegetation in an area causes greater runoff of water, thereby creating an increase in the potential for flooding.  This same process also erodes the soil of the region, causing further problems such as increased sedimentation in the water and less nutrients available in the soil for any organisms remaining in the area.

National forests  are also used for  rangeland for farmers.   The fees received from these grazing rights amount to  several million dollars annually, 25% of which is given to the state where the park is located.  This helps the state to alleviate the costs of infrastruc-
ture within its borders.

Forests are also vitally important in flood and erosion control.  The loss of vegetation in an area causes greater runoff of water, thereby creating an increase in the potential for flooding.  This same process also erodes the soil of the region, causing further problems such as increased sedimentation in the water and less nutrients available in the soil for any organisms remaining in the area.

National forests are also used for rangeland for farmers.  The fees received from these grazing rights amount to several million dollars annually, 25% of which is given to the state where the park is located.  This helps the state alleviate the costs of infrastructure within its borders.

Forests are also necessary as habitats for wildlife, and for this reason they must be protected.  In addition, they provide places of recreation for millions of people.  Revenue from our national parks is used to support many environmental programs.
 
 

Terrestrial Ecosystems	What Can Be Done?
Development	Loss of Biodiversity